Yab lonovit (Yablonovitch, E. et al. Phys. Rev. Lett. 1987, 58, 2059-2062.) and John (John, S. et al. Phys. Rev. Lett. 1987, 58, 2486-2489) presented the concept of photonic crystal in 1987. Bragg diffraction occurs at the dielectric interface of photonic crystal as a result of great disparity between potential field and dielectric constant and leads to photonic band gap capable of spreading and dispersing light, and therefore new physical phenomenon such as superprism phenomenon or negative refraction index dielectric effect is observed. For the next thirty years, photonic crystal has been attracted extensive attention and the method of preparation has been widely investigated. As advanced optical material, photonic crystal shows promising prospect of application on photonic crystal reflective device, photonic crystal filter, LED and photonic crystal fiber and becomes an important material to produce photonic device.
Velev (O. D. Velev, et al. Science, 2000, 287, 2240-2243.) added high concentration of PS nanospheres aqueous solution into fluorinated oil phase. As polymer droplet floats on the oil phase, PS nanospheres arrange regularly and micron scale photonic crystal microspheres are formed after water evaporation. Different colors and shapes of microspheres are obtained by adjusting the grain size of PS nanospheres and its concentration.
Velikov (K. P. Velikov, et al. Science, 2002, 296, 206-109.) produced binary superlattice by layer to layer self-assembly via PS nanospheres with different grain sizes as self-assembled unit.
Wang (J. Wang, et al. Macromol. Chem. Phys. 2006, 207, 596-604.) synthesized a series of core-shell nanospheres of different grain sizes with PS as core and PMMA as shell, and discovered that the polymer nanospheres could be stacked on matrix to form photonic crystal with long-range ordered. Further, color change of photonic crystal from red to blue can be realized by adjusting the grain sizes of polymer nanospheres.
Mihi (A. Mihi, et al. Adv. Mater. 2006, 18, 2244-2249.) dispersed SiO2 or sulfonated polystyrene nanospheres on volatile solvent and produces photonic crystal with color of being adjustable via spin coating.
Patent No. CN200510012021.6 disclosed a polymer colloid photonic crystal film with photonic band gap on UV-light by polymer emulsoid particle with hard core and soft shell. However, the polymer emulsoid particle is produced by three monomers with complicated feeding and temperature programming. Moreover, the final product is not pure enough as emulsifier and pH buffer are introduced into the system and the formation of colloid crystal is disturbed by impurity, which may limit the size of final film and its application. The polymer emulsoid particles are stacked together without chemical bonding, so that its mechanical strength is less than that of high-strength cross-linked polymer photonic crystal film of present invention.
Ordered arrangement of photonic crystal can be realized by self assembly since van der Waals force, hydrogen bond, electrostatic force and surface tension can be considered as its dynamics. The present invention provides a simple and efficient method for preparing high-strength cross-linked polymer photonic crystal film based on self assembly.